The present invention relates to a refrigerant storage vessel located in-line between the evaporator and the compressor in a typical refrigeration system. More particularly, the invention relates to a suction accumulator which separates the liquid components of the refrigerant from the gaseous components thereof and provides a storage or sump for the liquid refrigerant.
Most compressors adapted for use in refrigeration systems are designed for the compression of gaseous refrigerant. However, under some circumstances liquid refrigerant may flow from the evaporator into the suction inlet of the compressor. This condition, often referred to as slugging, may occur at start-up of the refrigeration system or during certain operating conditions of the system wherein the evaporator is flooded and excess liquid refrigerant enters the suction line returning to the compressor. If an accumulator is not provided, large quantities of condensed refrigerant return through the suction line to the crankcase of the compressor. When the compressor is restarted, the large quantity of liquid refrigerant present therein results in abnormally high pressures which frequently cause blown gaskets, broken valves, etc.
Suction accumulators, which are well known in the art, have been incorporated into refrigeration systems to act as storage reservoirs for liquid refrigerant which may be present in the suction line to prevent such liquid refrigerant from entering the compressor. Such accumulators permit the liquid refrigerant to change to its gaseous state before entering the compressor. A common type of accumulator comprises a vessel having a generally U-shaped tube received therein, one end of which is connected to the storage vessel and the other end of which is open to the interior of the vessel. As the incoming refrigerant flows into the vessel, the liquid component collects in the bottom thereof while the gaseous component is carried off through the U-tube and the outlet of the vessel to the compressor suction inlet. A bleed-through orifice in the wall of the U-tube, located in the lower portion of the vessel, meters a small quantity of liquid refrigerant into the stream of gaseous refrigerant flowing through the tube so that a larger slug of refrigerant is not introduced into the inlet of the compressor on start-up or during operation thereof. Such accumulators may furthermore provide for pressure equalization, whereby the pressure at the outlet of the suction accumulator is equalized with the pressure in the liquid storage vessel. This prevents higher pressures in the liquid from forcing liquid refrigerant into the suction inlet of the compressor when the compressor is turned off.
A problem associated with a refrigeration system of the type to which the present invention pertains, includes the presence of dirt particles, and the like, suspended in the refrigerant and entrained lubricating oil. When carried through the refrigeration system with the refrigerant, such dirt particles can cause premature mechanical wear or failure of system components, or impede the flow of refrigerant through the system, thereby causing system operating inefficiencies.
Various methods have been proposed for filtering dirt particles suspended in the refrigerant and lubricating oil of a refrigeration system, several of which are associated with the suction accumulator of the refrigeration system. For instance, it is known to provide a screen filter at the entry of the suction accumulator, whereby a screen essentially partitions the storage vessel between an entry chamber and a storage chamber. One problem with such an arrangement is that the filter screen is disposed within the refrigerant flow path, thereby causing an undesirable pressure drop in the refrigeration system. Furthermore, accumulation of the dirt particles on the filter screen could eventually cause clogging of the screen and a further pressure drop in the system.
Another approach to filtering dirt particles from a refrigeration system, involving the suction accumulator, is the provision of a filter at the location of the bleed through orifice located in the lower portion of the accumulator storage vessel. In such an accumulator, dirt particles are carried with the refrigerant into the vessel and are prevented from entering the bleed through orifice by means of a filter. However, the swirling, turbulent environment within the storage vessel can result in the dirt particles reentering the refrigeration system through the open end of the U-tube. Furthermore, the provided filter can become clogged, thereby interfering with the desired metering of the liquid refrigerant into the gaseous refrigerant flow path.
While prior art attempts to filter dirt particles from the refrigerant in a refrigeration system have been somewhat successful, it is desired to provide an improved suction accumulator that is capable of trapping and isolating dirt particles, and preventing their reintroduction into the refrigeration system.